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Saturday, May 27, 2017

21 INCH LG SUPER SLIM CRT TELEVISION DEAD NOW REPAIRED

This television was from a customer I had
repaired another television and was happy with my service and therefore when
this other one developed a problem he requested me to fix it if it was
possible.

Most
customers fear dead symptom equipment but from experience dead equipment are
easily repairable with main cause of dead television/equipment is power
related.

Therefore I
passed by his place and picked it so that I can do repair on my workbench.Upon
reaching my workbench I applied the power even before opening and indeed the
television was dead and no sign of life.

I opened the
set and went straight to the primary side of the power supply side looking for
any broken component and all looked good. I checked
the state of the main fuse and it was found open but not darkened inside.

Usually when
you find the main fuse is broken it is important to check if the switching
transistor is shorted (or the control I.C) You can
easily do this by testing across the middle leg (collector) and emitter while
still in circuit.

After doing
this test with my digital meter set to diode ranger I got a beep, to confirm if
it is indeed shorted I cut the middle leg with a side cutter to dis connect it
from the circuit.

This is
faster than soldering the whole transistor out in order to test it out of
circuit/ by cutting the middle leg is same as soldering out the whole
transistor out of the circuit.

With the
middle leg out of the circuit, re-tested again and still got a beep and with
this I confirmed the switching transistor was shorted.

The
transistor part number was C6091 and being not common in my market I replaced
it with D1710C, from my experience this is like universal replacement
transistor for all switching transistors so whenever I find the power supply is
using any funny switching transistor is usually replace it with D1710C without
thinking and it has always worked, I therefore keep several pieces of these at
any given time.

I continued
testing related components with this transistor and the nearest related
component as you can the figure below is the driver transistor C3807.

Again I
tested it between the middle (collector) leg of C3807 and the emitter and again
got a beep and this again confirmed to me that this transistor also is shorted
and need replacement.

After
replacement this I continued checked for any other fault component and could
not get any.

After
replacing the two transistors and the fuse, I decided to apply power and see if
the television will now power up and after applying power I realized that the
TV was already up and working

It's so refreshing to see someone actually repair these old TV's rather than just throwing them in the landfill. Unlike today's "modern technology", these old reliables were built to last a lifetime. Thanks for the great post!

Hey Humphrey,I really appreciate what you're doing, keep up the good job.....Now my Samsung CRT T.v has been having a problem lately (sometimes it turns on , sometimes it doesn't ),I opened it up and had a look at the circuit board. The switch is fine the fuse is okay , the two electrolytic capacitors are okay ....don't know where the problem is ......and where can I find you guy.